As more conferencing systems begin to offer one or more streams of the same media type (e.g., video), conferencing clients need to be capable of rendering more than one stream as offered by the conferencing systems in an inter-operable manner. Mechanisms such as grouping of SDP (session description protocol, as described in RFC 4566) media lines and SDP media content further help in achieving this goal. However, unless a conferencing client understands the context of how these streams ought to be rendered, the conferencing clients may not be able to render streams of which the client not aware.
Conventional multipoint control unit (MCU) architecture lack of an efficient, flexible protocol to modify the media mix in the mixer of the MCU such that entities can transmit media as specified or receive media as specified over time. One working group is working on solving the above deficiency by controlling the functions of a mixer (e.g., “play a prompt”, “expect DTMF”, “play this media”, etc.). However, the attempts to control or imitate functions of the mixer are then limited to the available functionality.